Leica DMI3000B Mode D'emploi page 72

7. Start-up
• Switch to the 10x objective (if not present, the
20x objective).
• Ensure that the condenser is at the correct
height. The condenser height adjustment lets
you set the condenser head to the height of
the nominal free working distance. (For an S23
condenser, for example, the distance between
the surface of the stage and the front lens of
the condenser is approx. 23 mm).
• Hold a piece of white paper (approx. 3-10
cm) under the light source (fi eld diaphragm).
A light ring should appear on the paper – if
not, check the power cable, the light source
and the fuse of the supply unit (CTR box) and
ensure that all of the parts are correctly con-
nected to one another.
• Open the fi eld diaphragm as far as possible un-
til the light ring reaches its maximum diameter.
• Next, hold the paper under the condenser,
directly on the stage. Open the aperture dia-
phragm as far as possible, until the light ring
has reached its maximum brightness. In order
to achieve maximum brightness, ensure that
no port is activated. The full light should be di-
rected to the VIS port.
• Check the magnifi cation changer to ensure
that the 1x tube lens is selected.
• Adjust the lenses of the eyepieces so that one
circle is visible in the eyepieces (not two!). If
you wear spectacles, remove the antiglare
hoods from the eyepiece tubes (or fold them
back).
• Ensure that the focus on the eyepieces is set
to ±0 (turn the upper part of the eyepiece tubes
until the silver ring is just covered).
72
• You should see light when looking through the
eyepieces at this point.
If the light is too bright, reduce it as required.
Remove all unneeded components from the light
path.
• Swing all fi lters (in the fi lter magazine of the
lamp housing or the fi lter holder of the con-
denser) out of the beam path.
• Set the condenser disk to the bright fi eld posi-
tion.
• If your microscope is equipped for DIC:
• Remove the polarizer.
• Remove the analyzer.
• Remove the objective prism (move the mag-
azine to the „empty" or „bright fi eld" posi-
tion).
• If your microscope is equipped for fl uores-
cence:
• Select an empty fi lter position (or a fi lter with
low transmission in the visible range, e.g. fi l-
ter A).
Now to begin with the actual Koehler illumina-
tion:
• Place your specimen on the stage and focus
so that you can see its details as clearly as
possible. You probably will not get a perfect im-
age at this point, as the illumination will not be
optimal (90a).
• Next, attempt to get a sharp image (or at least
a part of the image at the edge) by carefully
moving the condenser up and down (90.2). Try
this with a variety of fi eld diaphragm settings
until you get a clear, sharp image (91.b). This
may take a while!
• To center the sharp image, insert the centering
keys in the openings provided at either side of
the top part of the condenser (90.1). Move the
image into the center of the fi eld of view (91.c).
Next, open the fi eld dia phragm until the image
fi lls nearly the entire fi eld of view. The black